Several charts from Deutsche Bank's mammoth "Long-Term
Asset Return Study,” from strategists Jim Reid, Nick
Burns and Seb Baker, show how the improvements in farming
techniques have driven down food prices.

Efficiency has outstripped population growth, putting to bed old
18th century economic theories that the human birthrate would
explode and we would all end up scrabbling for a few grains
of wheat.

The analysts note (emphasis ours):

Intuitively this makes sense for agricultural products as
they are clearly renewable and although there are land
and yield constraints we would speculate that productivity gains
in harvesting these renewable products have outstripped
population growth.

Here's wheat prices look like in the the long term according to
the Deutsche Bank charts:

Deutsche Bank

Sugar has had an even sharper drop:

Deutsche Bank

While this is great for dinner, it makes predicting long
term trends in soft commodities much tougher.

The constant declines leave food commodities without a
steady historical average price to for traders return to in
normal trading conditions, so there's no reliable benchmark for
future prices.

The farmers threw eggs at police, drove tractors down busy
streets and set alight bales of hay before they were dispersed.
The European Commission pledged aid worth €500 million ($558
million, £363 million) for the farmers.